The US Embassy restricted the movement of its staff Wednesday and urged Americans to be vigilant a day after a bomb hit one of its vehicles in the first attack in more than two decades targeting American diplomats here. Two Lebanese and a Syrian were killed in the bombing, which took place as President Bush was touring the Middle East. The attack highlighted the growing chaos in Lebanon, which has descended into violence over the last three years after almost a decade of calm following its long civil war. US diplomats are deeply involved in the country's fractured politics, supporting the government against the Syrian-backed opposition. The sides have been deadlocked over choosing a new president. The armor-plated embassy car was damaged in the bombing on a north Beirut highway, and its Lebanese driver and an American theology teacher at a nearby church were among 26 people wounded. Two Lebanese and a Syrian bystander were killed. Lebanese troops set up checkpoints and diverted traffic Wednesday near the north Beirut seaside highway where the bomb exploded - one of the roads that embassy staff would have had to take to attend a farewell reception for the departing US ambassador scheduled later Tuesday. It was canceled. The targeted car was apparently one of the embassy vehicles that routinely scout roads before US diplomats travel, Lebanese security officials said. It was the first such attack in 23 years in Lebanon, where targeting Americans in the 1980s became so notorious, during the tail end of the country's 15-year civil war, that the United States imposed a blanket ban on Americans traveling to the country. It was lifted only in 1997. The embassy advisory did not specify how much its personnel were limited in movement. The embassy, about eight miles from the explosion site in the suburban hills northeast of Beirut, already is heavily fortified, protected by American and Lebanese security with a strong Lebanese army presence in the area. "The embassy ... reminds all Americans in Lebanon to maintain a high level of vigilance, especially when planning travel," the advisory said. "Americans are also advised to avoid popular gathering spots." Secretary of State Condoleezza Rice expressed outrage over the attack. "The United States will, of course, not be deterred in its efforts to help the Lebanese people, to help the democratic forces in Lebanon," she said in Saudi Arabia, where Bush was touring. Political tensions are high in Lebanon, more than a year into the crisis marked by a series of bombings and political assassinations that began in 2005. Most attacks have targeted anti-Syrian politicians and journalists. Syria effectively controlled its smaller neighbor for 29 years until its troops were forced to pull out in 2005 after the assassination of former Prime Minister Rafik Hariri. But the latest harkened back more to the bloody 1980s - when Lebanon was the site of some of the deadliest terror attacks against Americans ever, including the 1983 Marine barracks bombing that killed 241 U.S. service members. That same year, the U.S. Embassy was also hit by a car bomb, killing 63 people including 17 Americans. In 1984, the embassy's new compound at Aukar was also targeted by a suicide bombing, killing 12. The United States had deployed military units in Beirut at the time, in the aftermath of Israel's invasion of the country, but then-President Reagan withdrew them after the Marine barracks attack. The U.S. withdrew all diplomats from Beirut in September 1989 and did not reopen its embassy until 1991. Even before Tuesday's attack, U.S. diplomats in Lebanon were subject to strict security rules that prohibit them from bringing their children to live with them, and require them to travel with armed guards. In 2002, an American missionary, Bonnie Penner, was killed at a Christian center in the southern city of Sidon. Tuesday's bomb was hidden among garbage containers near the main Mediterranean coastal highway in north Beirut's predominantly Christian Dora-Karantina neighborhood. The powerful blast went off as the armor-plated U.S. Embassy SUV passed. The blast's brunt was taken by another vehicle behind, in which two Lebanese were killed, Lebanese security officials said. The explosion sent a pall of gray smoke over the highway, damaged several other cars, blew out nearby windows and knocked down facades of adjacent buildings in a largely industrial zone. The Syrian man who died had been riding a scooter on the road. Matthew Clason, a 28-year-old Minnesota native, said he was at the nearby National Evangelical Church where he teaches when the bomb went off. "The windows blew in and I fell down - I was knocked out," Clason told The Associated Press while sitting in the emergency room corridor of Jeitawi Hospital with bandages covering cuts on his head, face and right leg. His wife said Tuesday that they had only been in Lebanon for two weeks before the attack occurred. On Wednesday morning, Clason was back at the church, but refused to speak to the media as he stood in the courtyard with his wife and two daughters.